The presence of a monochromatic laser beam must be detected in a variety of applications. In a direct-detection technique for sensing the monochromatic laser beam, the laser beam is directly incident upon the sensing elements of a detector. The detector converts the incident laser energy to an electrical signal for further processing.
However, there can be difficulties in applying this direct-detection approach. At some times the laser beam may have too low a power density for the detector and be undetectable, while at other times it may have too high a power density for the detector and damage the detector. Another problem is that the detector may not be optimized for the specific wavelength of the monochromatic laser beam.
An alternative approach is required that does not suffer from the shortcomings of the direct-detection technique. The present invention fulfills this need, and further provides related advantages.